Changes of HBsAg and HBV DNA levels in Chinese chronic hepatitis B patients after 5 years of entecavir treatment

Hepatitis B surface antigen seroclearance: Relationship to hepatitis B e-antigen seroclearance and hepatitis B e-antigen-negative hepatitis

OBJECTIVES

The objective of this study was to determine factors associated with hepatitis B surface antigen (HBsAg) seroclearance after hepatitis B e-antigen (HBeAg) seroclearance.

METHODS

This is a cohort study of HBeAg-positive patients with HBeAg seroclearance. Factors associated with subsequent HBsAg seroclearance were examined.

RESULTS

A total of 775 patients were included. At 1, 5, 10, 15, 20, and 25 years after HBeAg seroclearance, the HBsAg seroclearance rate was 0.3, 1.3, 3.0, 8.9, 15.7, and 23.6%, respectively. The rate of HBsAg seroclearance was highest in those who underwent spontaneous HBeAg seroclearance and required no treatment afterward (group 1), compared with those who underwent treatment-induced HBeAg seroclearance (group 2), and those who required antiviral therapy after spontaneous HBeAg seroclearance (group 3). At 25 years after HBeAg seroclearance, the HBsAg seroclearance rate was 38.0, 14.9, and 0% in groups 1, 2, and 3, respectively (P<0.001). There was no difference in the rate of HBsAg seroclearance between those who received interferon-based therapy compared with nucleos(t)ide analogs. The median HBV DNA level was similar between those with and without HBsAg seroclearance. The median HBsAg level was significantly lower in those who had HBsAg seroclearance compared with those who did not achieve loss of HBsAg (2.81 vs. 3.52 log IU/ml, respectively, P=0.009). The area under receiver operating characteristic curve for HBsAg at 1 year after HBeAg seroclearance for predicting HBsAg seroclearance was 0.742, with an optimal cutoff of 751 IU/ml.

CONCLUSIONS

Spontaneous HBeAg seroclearance without need for subsequent antiviral therapy was associated with the highest rate of subsequent HBsAg seroclearance. Lower HBsAg levels were also associated with higher chance of HBsAg seroclearance.

[Clinical significance of hepatitis B surface antigen quantification in chronic hepatitis B]

Since the discovery of HBsAg in the early 1960s, presence of HBsAg in serum has only served to diagnose hepatitis B. Recent development in the quantitative measurement of serum HBsAg has enabled us to improve our understanding on the management of chronic hepatitis B. The surface antigen (sAg) level is at its highest in immune tolerance phase and decreases to the lowest level in immune control/inactive phase when HBeAg is cleared from the serum. Combination of serum sAg titer less than 1,000 IU/mL and serum HBV DNA less than 2,000 IU/mL can identify true inactive carrier from e antigen (eAg) negative hepatitis with diagnostic accuracy of 95%. During the natural course of chronic hepatitis B, changes or absolute level of sAg less than certain level can predict spontaneous sero-clearance of HBsAg. Although the decline of sAg is very slow in interferon (IFN)/pegylated interferon (PEG-IFN) or oral nucleos(-t)ide treated patients, interferon based therapy results in a greater decrease of sAg level and sAg loss. Lack of any decline in sAg titer during PEG-IFN therapy could identify the group of patients who do not response to IFN/PEG-IFN therapy. With the aid of serum HBV DNA, quantitative measurement of serum HBsAg level can be used to optimize the management of chronic hepatitis B in our daily practice.